# OpenTelemetry API for JavaScript

[![NPM Published Version][npm-img]][npm-url]
[![Apache License][license-image]][license-image]

This package provides everything needed to interact with the unstable OpenTelemetry Events API, including all TypeScript interfaces, enums, and no-op implementations. It is intended for use both on the server and in the browser.

## Beta Software - Use at your own risk

The events API is considered alpha software and there is no guarantee of stability or long-term support. When the API is stabilized, it will be made available and supported long-term in the `@opentelemetry/api` package and this package will be deprecated.

## Quick Start

Purposefully left blank until SDK is available.

## Version Compatibility

Because the npm installer and node module resolution algorithm could potentially allow two or more copies of any given package to exist within the same `node_modules` structure, the OpenTelemetry API takes advantage of a variable on the `global` object to store the global API. When an API method in the API package is called, it checks if this `global` API exists and proxies calls to it if and only if it is a compatible API version. This means if a package has a dependency on an OpenTelemetry API version which is not compatible with the API used by the end user, the package will receive a no-op implementation of the API.

## Advanced Use

### API Methods

If you are writing an instrumentation library, or prefer to call the API methods directly rather than using the `register` method on the Tracer/Meter/Logger Provider, OpenTelemetry provides direct access to the underlying API methods through the `@opentelemetry/api-events` package. API entry points are defined as global singleton objects `trace`, `metrics`, `logs`, `events`, `propagation`, and `context` which contain methods used to initialize SDK implementations and acquire resources from the API.

- [Events API Documentation][events-api-docs]

```javascript
const api = require("@opentelemetry/api-events");

/* A specific implementation of EventEmitterProvider comes from an SDK */
const eventEmitterProvider = createEventEmitterProvider();

/* Initialize EventEmitterProvider */
api.events.setGlobalEventEmitterProvider(eventEmitterProvider);
/* returns eventEmitterProvider (no-op if a working provider has not been initialized) */
api.events.getEventEmitterProvider();
/* returns an event emitter from the registered global event emitter provider (no-op if a working provider has not been initialized) */
const eventEmitter = api.events.getEventEmitter(name, version);

// logging an event in an instrumentation library
eventEmitter.emit({ name: 'event-name', domain: 'event-domain' });
```

## Useful links

- For more information on OpenTelemetry, visit: <https://opentelemetry.io/>
- For more about OpenTelemetry JavaScript: <https://github.com/open-telemetry/opentelemetry-js>
- For help or feedback on this project, join us in [GitHub Discussions][discussions-url]

## License

Apache 2.0 - See [LICENSE][license-url] for more information.

[discussions-url]: https://github.com/open-telemetry/opentelemetry-js/discussions
[license-url]: https://github.com/open-telemetry/opentelemetry-js/blob/main/LICENSE
[license-image]: https://img.shields.io/badge/license-Apache_2.0-green.svg?style=flat
[npm-url]: https://www.npmjs.com/package/@opentelemetry/api-logs
[npm-img]: https://badge.fury.io/js/%40opentelemetry%2Fapi-logs.svg
[logs-api-docs]: https://open-telemetry.github.io/opentelemetry-js/modules/_opentelemetry_api_logs.html
